1,096 research outputs found
Trip Generation of Selected Industrial Groups.
This paper determines the factors influencing commercial vehicle trip generation for selected industrial groups, and quantifies their effects using multiple regression analysis. Two methods of selecting the groups were adopted: one using eight of the Standard Industrial Classes; and one which attempted to put industries having similar vehicle generation characteristics into the same group, by subdividing SIC groups or by grouping together industries with similar manufacturing or trading processes. The survey combined an initial interview of firm's management about the operations of the firm with a recording by the firm of their travel data, using a sample of firms in the West Yorkshire metropolitan area. Of 22 relationships developed, 15 were considered acceptable descriptors of the variations in trip making, but only in 3 cases did a single variable (such as total floor area or total employees) account for more than 70 percent of the variation, and no single variable type gave the best fit for the various groups investigated
Siphonochilus aethiopicus (Zingiberaceae): observations on floral and reproductive biology
A taxonomic revision for the Flora of Southern Africa of Siphonochilus (Zingiberaceae) awaits publication (R.M. Smith, RBG, Edin., pers. comm. to ABC, 1987). In this revision the two southern African species, S. aethiopicus (Schweinf.) B.L. Burtt and S. natalensis (Schltr. & Schum.) Wood & Franks will be united. For the purposes of this article this conspecificity is assumed. S. aethiopicus has a distribution in Africa southwards from Senegal and Ethiopia to the Transvaal. Futher south wild populations are not now known, the species having disappeared from the natural flora of Natal. Rhizomes are extensively used in traditional African medicine and cultural practices. Floral and reproductive biology is poorly documented, but important if cultivated stocks in southern Africa are to be maintained. Monitoring of plants under cultivation and semi-natural conditions did not support the record of polygamy within the species. One type of flower only was produced by an individual rhizome. Bisexual flowers may mature to fruits containing viable seed that will germinate in situ. Ovaries of female flowers did not develop, suggesting apomixis does not operate in seed production. The internal surfaces of the staminodial tubes of bisexual flowers bore scattered glandular trichomes; those of female flowers densely placed multicellular papillae. Bisexual and female flowers are thus strikingly different in detailed structure as well as in general morphological form
Applications of a new fluorimetric enzyme assay for the diagnosis of aspartylglucosaminuria
L-Aspartic acid-β-7-amido-4-methylcoumarin is a sensitive and specific fluorogenic substrate for lysosomal glycoasparaginase (aspartylgluco-saminidase). Fibroblasts and leukocytes from 8 patients with aspartylglucosaminuria, showed 1-7% of the mean normal glycoasparaginase activity. Heterozygotes showed intermediate activities. Glycoasparaginase activity in chorionic villi, cultured trophoblasts, cultured amniotic fluid cells and amniotic fluid was readily detectable, indicating that prenatal analysis of aspartylglucosaminuria should be possible with this assay. β-Aspartyl-4-methylumbelliferone was synthesized but this potential substrate can not be used to assay glycoasparaginase since it hydrolyses spontaneously
Mutations of the BRAF gene in human cancer
Cancers arise owing to the accumulation of mutations in critical genes that alter normal programmes of cell proliferation, differentiation and death. As the first stage of a systematic genome-wide screen for these genes, we have prioritized for analysis signalling pathways in which at least one gene is mutated in human cancer. The RAS RAF MEK ERK MAP kinase pathway mediates cellular responses to growth signals. RAS is mutated to an oncogenic form in about 15% of human cancer. The three RAF genes code for cytoplasmic serine/threonine kinases that are regulated by binding RAS. Here we report BRAF somatic missense mutations in 66% of malignant melanomas and at lower frequency in a wide range of human cancers. All mutations are within the kinase domain, with a single substitution (V599E) accounting for 80%. Mutated BRAF proteins have elevated kinase activity and are transforming in NIH3T3 cells. Furthermore, RAS function is not required for the growth of cancer cell lines with the V599E mutation. As BRAF is a serine/threonine kinase that is commonly activated by somatic point mutation in human cancer, it may provide new therapeutic opportunities in malignant melanoma
Quantum Coherence in a Single Ion due to strong Excitation of a metastable Transition
We consider pump-probe spectroscopy of a single ion with a highly metastable
(probe) clock transition which is monitored by using the quantum jump
technique. For a weak clock laser we obtain the well known Autler-Townes
splitting. For stronger powers of the clock laser we demonstrate the transition
to a new regime. The two regimes are distinguished by the transition of two
complex eigenvalues to purely imaginary ones which can be very different in
magnitude. The transition is controlled by the power of the clock laser. For
pump on resonance we present simple analytical expressions for various
linewidths and line positions.Comment: 6 figures. accepted for publication in PR
Detailed Examination of Transport Coefficients in Cubic-Plus-Quartic Oscillator Chains
We examine the thermal conductivity and bulk viscosity of a one-dimensional
(1D) chain of particles with cubic-plus-quartic interparticle potentials and no
on-site potentials. This system is equivalent to the FPU-alpha beta system in a
subset of its parameter space. We identify three distinct frequency regimes
which we call the hydrodynamic regime, the perturbative regime and the
collisionless regime. In the lowest frequency regime (the hydrodynamic regime)
heat is transported ballistically by long wavelength sound modes. The model
that we use to describe this behaviour predicts that as the frequency goes to
zero the frequency dependent bulk viscosity and the frequency dependent thermal
conductivity should diverge with the same power law dependence on frequency.
Thus, we can define the bulk Prandtl number as the ratio of the bulk viscosity
to the thermal conductivity (with suitable prefactors to render it
dimensionless). This dimensionless ratio should approach a constant value as
frequency goes to zero. We use mode-coupling theory to predict the zero
frequency limit. Values of the bulk Prandtl number from simulations are in
agreement with these predictions over a wide range of system parameters. In the
middle frequency regime, which we call the perturbative regime, heat is
transported by sound modes which are damped by four-phonon processes. We call
the highest frequency regime the collisionless regime since at these
frequencies the observing times are much shorter than the characteristic
relaxation times of phonons. The perturbative and collisionless regimes are
discussed in detail in the appendices.Comment: Latex with references in .bib file. 36 pages, 8 figures. Submitted to
J. Stat. Phys. on Sept. 2
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Simple model of adsorption on external surface of carbon nanotubes: a new analytical approach basing on molecular simulation data
Nitrogen adsorption on carbon nanotubes is wide- ly studied because nitrogen adsorption isotherm measurement is a standard method applied for porosity characterization. A further reason is that carbon nanotubes are potential adsorbents for separation of nitrogen from oxygen in air. The study presented here describes the results of GCMC simulations of nitrogen (three site model) adsorption on single and multi walled closed nanotubes. The results obtained are described by a new adsorption isotherm model proposed in this study. The model can be treated as the tube analogue of the GAB isotherm taking into account the lateral adsorbate-adsorbate interactions. We show that the model describes the simulated data satisfactorily. Next this new approach is applied for a description of experimental data measured on different commercially available (and characterized using HRTEM) carbon nanotubes. We show that generally a quite good fit is observed and therefore it is suggested that the observed mechanism of adsorption in the studied materials is mainly determined by adsorption on tubes separated at large distances, so the tubes behave almost independently
Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector
The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements
Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV
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Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks
Peer reviewe
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